fructify vs richen

fructify

verb
  • To make productive or fruitful. 

  • To bear fruit; to generate useful products or ideas. 

richen

verb
  • To make or render rich or richer. 

  • To become rich or richer; become superior in quality, condition or effectiveness. 

  • To gain richness; become heightened or intensified in brilliancy. 

How often have the words fructify and richen occurred in a corpus of books? (source: Google Ngram Viewer )